ADP5587ACPZ-R7 datasheet(10/24 Pages) AD

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ADP5587

Rev. B | Page 10 of 24

Auto-Increment

The ADP5587 features automatic increment during I2C read

access, which allows the user to increment the address pointer

without the need to send a read command for subsequent

addresses. This minimizes processor intervention and, therefore,

saves processor bandwidth and current drain. Bit 7 of Register 0x01

must be set to initiate auto-increment (see Figure 17 for the full

write and read sequence).

Key Event Interrupt

On a key event (KE) interrupt, the processor reads the interrupt

status register to determine the cause of the interrupt. If the

KE_INT bit in Register 0x02 is set, the processor reads the key

event count from the KEC [3:0] field in Register 0x03 to determine

the number of events. After reading all the events from the

FIFO, it then reads the KEC field again (in Register 0x03) to

make sure that no new events have come in. After all the events

are read, the KEC field is decremented to zero (KEC = 0), and

the KE_INT bit can be cleared by writing a 1 to it. Both key

presses and key releases are capable of generating key event

interrupts. The KE_INT bit cannot be cleared, and the INT pin

cannot be deasserted, until the FIFO is cleared of all events.

KEYPAD MODE

KEC

REG. 0x1D

THROUGH REG. 0x1F

REG. 0x03

READ KE(s) TO CLEAR

INT DRIVE

KE_INT

REG. 0x02

WRITE 1 TO CLEAR

KE_IEN

REG. 0x01

AND

Figure 11. Key Event Interrupt Generation

START

MASK TIMER = 0

KEY PRESS

DETECTED

YES

GENERATE

KE INTERRUPT

START MASK TIMER

MASK TIMER

EXPIRES

MASK TIMER

EXPIRES

GENERATE

KEYLOCK INTERRUPT

FIRST UNLOCK

KEY DETECTED

SECOND UNLOCK

KEY DETECTED

START UNLOCK1 TO UNLOCK2

UNLOCK1 TO

UNLOCK2

TIMER EXPIRES

KEY PRESS

DETECTED

START UNLOCK1 TO UNLOCK2

FIRST UNLOCK

KEY DETECTED

GENERATE

KEYLOCK INTERRUPT

SECOND UNLOCK

KEY DETECTED

UNLOCK1 TO

UNLOCK2

TIMER EXPIRES

Figure 12. Keypad Lock Interrupt Mask Timer Flowchart

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